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q a dc shunt machine has an armature winding resistance of 012 and a shunt-eld winding resistance of 50 the machine may be run on 250-v mains as
q a three-phase ac motor used to drive a draft fan is connected to a 60-hz voltage supply at noload the speed is 1188 rmin at full load the speed
a synchronous generator has a rotor with six poles and operates at 60 hza determine the speed of prime mover of the generatorb repeat part a if the
a three-phase wound-rotor induction machine with its shaft rigidly coupled to the shaft of a three-phase synchronousmotor is used to change balanced
a four-pole three-phase wound-rotor induction machine is to be used as a variable-frequency supply the frequency of the supply connected to the
induction motors are often braked rapidly by a technique known as plugging which is the reversal of the phase sequence of the voltagesupplying the
consider a three-phase induction motor with a normal torque-speed characteristic neglecting the effects of stator resistance and leakage reactance
a four-pole three-phase inductionmotor is energized from a 60-hz supply it is running at a load condition for which the slip is 003 determinea the
q a three-phase 60-hz induction motor runs at almost 1800 rmin at no load and at 1710 rmin at full loada how many poles does the motor haveb what is
q a three-phase 50-hz induction motor has a full load speed of 700 rmin and a no-load speed of 740 rmina how many poles does the machine haveb find
a communication system for a voice-band 3 khz channel is designed for a received snr ebn0 at the detector of 30 db when the transmitter power is ps
to have the same value of pe show that ebn0 in a coherent-ask system has to be twice that in a coherent psk
if ebn0 20 in a coherent ask system find the value of ebn0 that is needed in a noncoherent ask system to yield the same value of pe as the coherent
by a simple time multiplexing of natural samples over a single line a large radar site transmits 85 analog signals each with 200-hz bandwidth if the
four voicemessages each with 3-khz bandwidth are to be sampled at nyquist rate and time- multiplexed with samples taken at twice the nyquist rate
the expression given in problem for s0n0pcm is plotted for a sinusoidal message in figure to show the performance curves for a pcm system using a
an audiomessage is band-limited to 15 khz sampled at twice the nyquist rate and encoded by a 12-bit natural binary code that corresponds to lb 212
determine the number of bits of a natural binary encoder that works with the quantizera if the extreme levels are plusmn31 v with a step size of 02
if a compressor in a system can change a message crest factor from 32 to 2 while maintaining its peak amplitude constant find the decibels of
a quantizer has 130 quantum levels that exactly the extremes of a symmetrically uctuating message with step size deltav 004 vdetermine the
q when the quantum step size deltav and the step size of f t are the same as in the quantizer is said to have a gain of unity if on the other hand
q the quantum levels of a quantizer are separated by the step size deltav 02 v with the lowest and highest levels of-33 v and 33 v respectivelya
q if an analog message that has a spectral extent of 15 khz is sampled at three times the nyquist rate determine the sampling
find the minimum rate of sampling that must be used to convert the message into digital forma if an audio message has a spectral extent of 3 khzb if
a tdm signal of the type is formed by samplingm voice signals at fs 8 khz if the tdm signal then modulates the amplitude of a 4-mhz carrier for